With underscores, Googleâ€™s programmer roots are showing. Lots of computer programming languages have stuff like _MAXINT, which may be different than MAXINT. So if you have a url like word1_word2, Google will only return that page if the user searches for word1_word2 (which almost never happens). If you have a url like word1-word2, that page can be returned for the searches word1, word2, and even â€œword1 word2â€³.

So, I’m going to head back and change the title format from underscores to hyphens.